Rosemont, which is planning to build a $1.2 billion mine near Tucson, had been issued Arizona Department of Environmental Quality permit. The approval was challenged by Save The Scenic Santa Ritas group, which claimed that the figures used for the modelling used by the agency was faulty. The environmental group argued that the modelling inputs, which were provided to Arizona's regulatory agency, were neither representative nor conservative.

Jude Crane McClennen of the Superior Court of Arizona, Maricopa County, agreed.

"Based on the foregoing, this Court concludes there was not substantial evidence to support the action of the AzDEQ, and the action of the AzDEQ was contrary to law, was arbitrary and capricious, and was an abuse of discretion," wrote the judge in his ruling.